/*
 // jQuery Ajax File Uploader
 //
 // @author: Jordan Feldstein <jfeldstein.com>
 //
 //  - Ajaxifies an individual <input type="file">
 //  - Files are sandboxed. Doesn't matter how many, or where they are, on the page.
 //  - Allows for extra parameters to be included with the file
 //  - onStart callback can cancel the upload by returning false
 */


(function($) {
    $.fn.ajaxfileupload = function(options) {
        var settings = {
            params: {},
            action: '',
            onStart: function() { },
            onComplete: function(response) { },
            onCancel: function() { },
            validate_extensions : true,
            valid_extensions : ['gif','png','jpg','jpeg'],
            submit_button : null
        };

        var uploading_file = false;

        if ( options ) {
            $.extend( settings, options );
        }


        // 'this' is a jQuery collection of one or more (hopefully)
        //  file elements, but doesn't check for this yet
        return this.each(function() {
            var $element = $(this);

            // Skip elements that are already setup. May replace this
            //  with uninit() later, to allow updating that settings
            if($element.data('ajaxUploader-setup') === true) return;

            $element.change(function()
            {
                // since a new image was selected, reset the marker
                uploading_file = false;

                // only update the file from here if we haven't assigned a submit button
                if (settings.submit_button == null)
                {
                    upload_file();
                }
            });

            if (settings.submit_button == null)
            {
                // do nothing
            } else
            {
                settings.submit_button.click(function(e)
                {
                    // Prevent non-AJAXy submit
                    e.preventDefault();

                    // only attempt to upload file if we're not uploading
                    if (!uploading_file)
                    {
                        upload_file();
                    }
                });
            }

            var upload_file = function()
            {
                if($element.val() == '') return settings.onCancel.apply($element, [settings.params]);

                // make sure extension is valid
                var ext = $element.val().split('.').pop().toLowerCase();

                // console.log( $element.val(),settings.valid_extensions,ext,$.inArray(ext, settings.valid_extensions) );
                if(true === settings.validate_extensions && $.inArray(ext, settings.valid_extensions) == -1)
                {
                    // Pass back to the user
                    settings.onComplete.apply($element, [{status: false, message: '上传格式应为 ' + settings.valid_extensions.join(', ') + '.'}, settings.params]);
                } else
                {
                    uploading_file = true;

                    // Creates the form, extra inputs and iframe used to
                    //  submit / upload the file
                    wrapElement($element);

                    // Call user-supplied (or default) onStart(), setting
                    //  it's this context to the file DOM element
                    var ret = settings.onStart.apply($element, [settings.params]);

                    // let onStart have the option to cancel the upload
                    if(ret !== false)
                    {
                        $element.parent('form').submit(function(e) { e.stopPropagation(); }).submit();
                    }
                }
            };

            // Mark this element as setup
            $element.data('ajaxUploader-setup', true);

            /*
             // Internal handler that tries to parse the response
             //  and clean up after ourselves.
             */
            var handleResponse = function(loadedFrame, element) {
                var response, responseStr = $(loadedFrame).contents().text();
                try {
                    //response = $.parseJSON($.trim(responseStr));
                    response = JSON.parse(responseStr);
                } catch(e) {
                    response = responseStr;
                }

                // Tear-down the wrapper form
                element.siblings().remove();
                element.unwrap();

                uploading_file = false;

                // Pass back to the user
                settings.onComplete.apply(element, [response, settings.params]);
            };

            /*
             // Wraps element in a <form> tag, and inserts hidden inputs for each
             //  key:value pair in settings.params so they can be sent along with
             //  the upload. Then, creates an iframe that the whole thing is
             //  uploaded through.
             */
            var wrapElement = function(element) {
                // Create an iframe to submit through, using a semi-unique ID
                var frame_id = 'ajaxUploader-iframe-' + Math.round(new Date().getTime() / 1000)
                $('body').after('<iframe width="0" height="0" style="display:none;" name="'+frame_id+'" id="'+frame_id+'"/>');
                $('#'+frame_id).get(0).onload = function() {
                    handleResponse(this, element);
                };

                // Wrap it in a form
                element.wrap(function() {
                    return '<form action="' + settings.action + '" method="POST" enctype="multipart/form-data" target="'+frame_id+'" />'
                })
                // Insert <input type='hidden'>'s for each param
                    .before(function() {
                        var key, html = '';
                        for(key in settings.params) {
                            var paramVal = settings.params[key];
                            if (typeof paramVal === 'function') {
                                paramVal = paramVal();
                            }
                            html += '<input type="hidden" name="' + key + '" value="' + paramVal + '" />';
                        }
                        return html;
                    });
            }



        });
    }
})( jQuery )
